- Pour stock into a sauce pan and bring to a simmer.
- Add the lemongrass, the galangal ginger, the kaffir lime leaves and the chilli paste, and allow to simmer between 1 and 2 minutes
- Add the prawns, the fish sauce, the sugar, the lime juice, and simmer for two minutes.
- Add the mushrooms, the tomato, the coconut milk, the bird's eye chilies and simmer for another minute
- Add the coriander leaves or cilantro leaves, the green onions and turn off the heat.
- Taste the soup and adjust the flavors. You may add more lime juice, fish sauce or chilies if needed. Taste and serve.